How can I recover lost tmodloader world and characters?

TModLoader effectively replaces the official Terraria.exe with a custom, mod-enabled version. Steam's "verify files" feature fixes any files in the installation path that are different from what the base installation expects. This means that TModLoader will be removed.

TModLoader saves modded players and worlds in a different folder than the base Terraria game. This is so that modded and base files don't intermingle. Due to this separation, you won't be able to see modded content from the base installation (which you currently have), and you can't see base content if you have a modded installation (TModLoader).

Luckily, these files are not included in Steam's file verification, so theoretically all you'll have to do to see the modded content again is to reinstall TModLoader (and possibly the mods you were using).